1. Field of the Invention
The present invention relates to crystals, amorphous substances, salts, and hydrates of salt of methyl N-[3-(6,7-dimethoxy-2-methylaminoquinazolin-4-yl)phenyl]terephthalamic acid.
2. Related Background Art
Compounds having an inhibitory action against phosphodiesterase 4 (PDE4) have been expected to be useful for treating allergic diseases such as atopic dermatitis. For example, Patent Document 1 discloses a compound having the following structural formula as a compound having a PDE4 inhibitory action.

Further, Patent Document 2 describes that the compound having a PDE4 inhibitory action described in Patent Document 1 is useful for treating allergic diseases.    [Patent Document 1] WO 99/37622    [Patent Document 2] WO 06/093226